Safety and occupational healthSH-003

Preheater blockage and hot-material release

San Juan Cement Company · Cantera Espinosa, Dorado, Puerto Rico, USA · 1996

Use this record when

The decision this case can inform

Use this record when reviewing occupancy, instrumentation, access, or blockage response around a preheater, kiln inlet, or cooler exposed to hot-material release.

Evidence scope

Final MSHA fatal-accident record describing a specific event chain. It identifies failed defenses but does not supply a transferable blockage-clearing procedure.

Source-supported facts

What the public record actually establishes

4 sourced points
  1. F1

    A preheater-to-kiln blockage released material estimated at about 900°C into an occupied kiln and cooler area.

  2. F2

    Two workers died and three were burned.

  3. F3

    Flow monitors for cyclones 3 and 4 had been disengaged, and the warning arrangement depended on manual action.

  4. F4

    A temporary work platform lacked the permanent access and guardrail protection available in the original arrangement.

Structured interpretation

Facts and reported results are kept separate from the lesson a plant may choose to test.

01

Operating context

A preheater-to-kiln material blockage developed while maintenance personnel occupied the kiln and cooler area.

02

Intervention or finding

MSHA identified sudden release of blocked hot material as the direct cause; disabled flow indication, a temporary platform, and lack of fall protection increased exposure and severity.

03

Documented result

Two workers died and three were burned when hot material was expelled into the occupied area.

04

Plant interpretation

Treat blocked or hung hot material as stored energy and control every credible release path before allowing occupancy.

05

Transfer boundary

Does not prescribe a blockage-clearing method; local rules and competent engineering govern.

Before applying the lesson

Questions to verify at your plant

These are decision checks, not operating instructions. Resolve them through local risk assessment, technical review, and authorization.

  1. 01

    What independent indications reveal restricted flow or accumulating hot material, and are any bypassed?

  2. 02

    Which occupied areas lie in a credible release path if a blockage clears without warning?

  3. 03

    Who has authority to establish, verify, and release the exclusion boundary?

  4. 04

    Have temporary access changes been engineered and reviewed against the original protection basis?